A compound comprising a composition Ax(M′1-aM″a)y(XD4)z, Ax(M′1-aM″a)y(DXD4)z, or Ax(M′1-aM″a)y(X2D7)z, and have values such that x, plus y(1−a) times a formal valence or valences of M′, plus ya times a formal valence or valence of M″, is equal to z times a formal valence of the XD4, X2D7, or DXD4 group; or a compound comprising a composition (A1-aM″a)xM′y(XD4)z, (A1-aM″a)xM′y(DXD4)z (A1-aM″a)xM′y(X2D7)z and have values such that (1−a)x plus the quantity ax times the formal valence or valences of M″ plus y times the formal valence or valences of M′ is equal to z times the formal valence of the XD4, X2D7 or DXD4 group. In the compound, A is at least one of an alkali metal and hydrogen, M′ is a first-row transition metal, X is at least one of phosphorus, sulfur, arsenic, molybdenum, and tungsten, M″ any of a Group IIA, IIIA, IVA, VA, VIA, VIIA, VIIIA, IB, IIB, IIIB, IVB, VB, and VIB metal, D is at least one of oxygen, nitrogen, carbon, or a halogen, 0.0001